Downlink subframe shortening in time-division duplex (TDD) systems

Abstract

A guard period for switching between uplink and downlink subframes is created by shortening a downlink subframe, i.e., by not transmitting during one or more symbol intervals at the end of the subframe. A grant message includes signaling indicating when a shortened subframe is being transmitted. An example method is implemented in a receiving node configured to receive data from a transmitting node in subframes having a predetermined number of symbol intervals. In an LTE system, this receiving node may be a UE, and the subframes are downlink subframes. This example method includes determining that a received subframe is to be shortened, relative to the predetermined number of symbol intervals and, in response to this determination, disregarding a last part of the received subframe by disregarding one or more symbols at the end of the received subframe when processing the received subframe.

What is claimed is: 
     
       1. A method, in a user equipment (UE) configured to receive data from a base station in subframes, wherein a predetermined number of symbol intervals is utilized in a normal subframe, the method comprising:
 receiving, in a subframe, a grant message scheduling the UE to receive data in the subframe and containing information indicating that one or more symbol intervals at the end of the subframe are to be disregarded; and 
 in response to the grant message, disregarding symbols in one or more symbol intervals at the end of the subframe when processing the subframe. 
 
     
     
       2. The method of  claim 1 , wherein the information specifies a number of symbol intervals that are to be disregarded. 
     
     
       3. The method of  claim 1 , further comprising switching from reception mode to transmission mode during the one or more disregarded symbol intervals at the end of the subframe. 
     
     
       4. The method of  claim 1 , wherein the grant message is included in a beginning portion of the subframe. 
     
     
       5. A method in a base station configured to transmit data to a user equipment (UE) in subframes, wherein a predetermined number of symbol intervals is utilized in a normal subframe, the method comprising:
 transmitting to the UE, in a subframe, a grant message scheduling the UE to receive data in the subframe and containing information indicating that one or more symbol intervals at the end of the subframe are to be disregarded. 
 
     
     
       6. The method of  claim 5 , wherein the information specifies a number of symbol intervals that are to be disregarded. 
     
     
       7. The method of  claim 5 , wherein the grant message is comprised in a beginning portion of the subframe. 
     
     
       8. A user equipment (UE) comprising a receiver circuit configured to receive data from a base station in subframes, wherein a predetermined number of symbol intervals is utilized in a normal subframe, the UE further comprising a processing circuit configured to control the receiver circuit and to:
 receive, in a subframe, a grant message scheduling the UE to receive data in the subframe and containing information indicating that one or more symbol intervals at the end of the subframe are to be disregarded; and, 
 in response to the grant message, disregard symbols in one or more symbol intervals at the end of the subframe when processing the subframe. 
 
     
     
       9. The UE of  claim 8 , wherein the information specifies a number of symbol intervals that are to be disregarded. 
     
     
       10. The UE of  claim 8 , wherein the processing circuit is further configured to:
 control the receiver circuit to switch off a reception mode, and 
 control a transmitter circuit to switch on a transmission mode during the one or more disregarded symbol intervals at the end of the subframe. 
 
     
     
       11. The UE of  claim 8 , wherein the grant message is included in a beginning portion of the subframe. 
     
     
       12. A base station, comprising a transmitter circuit configured to transmit data to a user equipment (UE) in subframes, wherein a predetermined number of symbol intervals is utilized in a normal subframe, the base station further comprising a processing circuit configured to control the transmitter circuit and to:
 transmit, via the transmitter circuit to the UE, in a subframe, a grant message scheduling the UE to receive data in the subframe and containing information indicating that one or more symbol intervals at the end of the subframe are to be disregarded. 
 
     
     
       13. The base station of  claim 12 , wherein the information specifies a number of symbol intervals that are to be disregarded. 
     
     
       14. The base station of  claim 12 , wherein the grant message is comprised in a beginning portion of the subframe. 
     
     
       15. A non-transitory computer-readable medium comprising, stored thereupon, a computer program for a user equipment (UE) configured to receive data from a base station in subframes, wherein a predetermined number of symbol intervals is utilized in a normal subframe, the computer program comprising computer program code that, when executed by a processor of the UE, causes the UE to perform the steps of:
 receiving, in a subframe, a grant message scheduling the UE to receive data in the subframe and containing information indicating that one or more symbol intervals at the end of the subframe are to be disregarded; and 
 in response to the grant message, disregarding symbols in one or more symbol intervals at the end of the subframe when processing the subframe.